Method and apparatus for decontaminating a rinse liquid

ABSTRACT

Method for rinsing plated work and decontaminating the rinse liquid by progressively immersing the work in a series of tanks, each of which has an inner rinsing or treating shell filled to overflowing and an outer shell. Immersion of the work in an inner rinsing shell causes the rinse liquid to overflow into its respective outer shell and also causes liquid in the outer shell to flow to the next succeeding outer shell in the series of tanks, the outer shells having piping connecting the outlet of one outer shell to the inlet of the outer shell of an adjacent tank. The rinse liquid in the outer shells is treated batchwise by the addition of chemical agents until it is sufficiently decontaminated to be disposed of.

United States Ptet [1 1 [111 3,849,197 Sorrentino Nov. 19, 1974 METHOD AND APPARATUS FOR 3,715,308 2/1973 Sulfaro et al. 210/61 x DECONTAMINATING A RINSE LIQUID Inventor: Benjamin J. Sorrentino, 43 Vermont Ave., Stratford, Conn. 06497 Filed: Mar. 8, 1973 Appl. N0.: 339,402

References Cited UNITED STATES PATENTS Primary Examiner-S. Leon Bashore Assistant Examiner-Marc Caroff Attorney, Agent, or Firm-Arthur A. Johnson [5 7] ABSTRACT Method for rinsing plated work and decontaminating the rinse liquid by progressively immersing the work in a series of tanks, each of which has an inner rinsing or treating shell filled to overflowing and an outer shell. Immersion of the work in an inner rinsing shell causes the rinse liquid to overflow into its respective outer shell and also causes liquid in the outer shell to flow to the next succeeding outer shell in the series of tanks, the outer shells having piping connecting the outlet of one outer shell to the inlet of the outer shell of an adjacent tank. The rinse liquid in the outer shells is treated batchwise by the addition of chemical agents until it is sufficiently decontaminated to be disposed of.

10 Claims, 5 Drawing Figures l'l'l'n 'u g PATENTEL, MN I 91974 SHEET 1 0f 3 llll'l METHOD AND APPARATUS FOR DECONTAMINATING A RINSE LIQUID This invention relates to the problem of rinsing work which has been plated to remove any perceptible trace of the chemical used in the plating or rinsing process, whereby the rinse water may be disposed of without adversely affecting the ecology.

Heretofore chemically contaminated rinse water used in plating processes was collected in large tanks where it was held and treated in an effort to decontaminate it sufficiently to be safely disposed of in a sewer or elsewhere. However, this bulk treatment was uncertain because, in view of the large quantity of liquid involved, there was no satisfactory way of determining whether all the water was sufficiently decontaminated. It was troublesome because it was necessary to test the liquid from time to time to determine the degree to which it has been decontaminated. It was also expensive because the large holding tank occupied a large area which could be used for more productive purposes.

An object of this invention is to obviate the disadvantages arising from the use of a large holding tank and to facilitate the treatment of the rinse water in such a way as to insure that the discharged water would not adversely affect the ecology of the area in which the work is performed.

A feature of this invention is the treatment of the rinse water progressively in relatively small batches and in a series of relatively small tanks in which it may be chemically treated and/or held and in which its chemical condition may be examined from time to time to determine the progress of the decontamination so that additional neutralizing material may be added to the liquid in the several tanks.

Another feature of this invention is the provision for the purpose aforesaid of tanks which have an inner shell and an outer shell, the inner shell serving to receive fresh rinse water and/or chemical materials to decontaminate the work immersed in the inner shells, the work being treated and rinsed as it proceeds from tank to tank.

Another feature of this invention is the provision of tanks having inner and outer shells in which the top of the outer shell is closed to prevent liquid in the inner tank from overlowing into the outer tank whereby the work may be treated with acids, chromates, etc. in the post-plating process, the outer shell in such tanks serving as holding tanks during which the decontaminates may act on the rinse water passing through them. The closed outer shells may be interspersed with other outer shells which are open at the top so that the decontaminating materials may be added to the rinse water flowing through such tanks.

These and other features and advantages which will hereinafter appear are accomplished by providing a series of tanks in which the work may be immersed, said tanks having inner and outer shells, the latter having inlet and outlet means whereby the liquid may pass from the outer shell of one tank to the other shell of an adjacent tank, the upper end of the inner shell in some situations being lower than the upper end of the outer shells whereby when the inner shell is filled with liquid to overflowing, work immersed in the inner shell will cause the liquid to overflow into the outer shell, the outer shell being provided with probes for use in testing the progress of the decontamination of the liquid passing through the outer shells, provision being made to discharge the decontaminated rinse liquid through a filter into a sewer or elsewhere for reuse at the end of the process or at intermediate points in the process.

According to the present invention in its broader aspects, the tanks may be separate structures interconnected by inlet and outlet piping or they may be formed by separator plates in one large structure forming a plurality of compartments in which the water may be separately tested and treated. In the case of the individual tanks, the level of the water in the outer tanks-is controlled by the position of the outlet piping, and in the case of a compartmentized unitary tank the level is controlled by the height and position of the separator plates. In either case, rinse water flows in relatively small batches from tank to tank or from compartment to compartment.

In another aspect of the present invention, each of the individual tanks comprises an outer shell for bolding and treating the rinse water and an inner shell which is placed within the outer shell and has an open top which is located at a level lower than the top of the outer shell and above the level of the water in the outer shell. The inner shell is large enough to receive a batch of plated work and its carrier and may be filled to overflowing with water so that when the work and the carrier are inserted in the inner shell the water in the latter will overflow into the outer shell, the water in the inner shell being replaced by fresh water while the work is being transferred from tank to tank.

Since the successive batches of work are immersed in and removed from the inner shells of said tanks, the volume of water delivered periodically from the last of a series of tanks will depend on the number of open top outer shells times the displacement of the batches of work and their carriers.

The length of time for the treatment in each inner shell will depend on the longest dwell period in the plating process, except where a shorter period is desirable.

According to the present invention, when the work is to be treated with acids, chromic material and the like, the tops of the outer shells containing such material are closed to prevent the latter from overflowing into and contaminating the rinse water in the outer shell which in such situations, act merely as holding tanks for the rinse water being treated.

By having the inner shells located within the outer shells, considerable floor space may be saved.

ln operation, after the inner shells have been filled with water to overflowing and the outer shells filled to a level determined by the positions of the outlet in the last tank of a series, after the work is removed from a plating tank it is conveyed to the first rinsing tank and deposited in the inner shell thereof. Then, after the next step of the plating cycle is completed, the work from a plating tank and the work in the inner shell of the first rinsing tank are removed from their respective tanks, the workfrom the plating tank being immersed in the first rinsing tank and the work from the latter being transferred to a second rinsing tank. At the next advancement of the work, the work from the plating tank is deposited in the first rinsing tank, the work from the latter may then be deposited in the second rinsing tank, and the work from the latter goes to the third tank or neutralizing tank. The latter having the outer shell closed at the top, the inner shell may contain decontaminating material as well as water. The batches of work each thus intermittently travel to successive tanks where they are treated and/or rinsed.

While the work is thus progressing, the rinse water is flowing through the outer shells of the tanks and is being treated with the decontaminating chemicals applied to the shells, the tops of which are open for periods of time depending on the number of rinsing tanks in the series and the time required in the plating steps. The quantity of rinse water passing from the system depends largely upon the amount of water displaced by the work and its carrier and the number of open top outer shells in the series.

Each outer shell may contain probing means for testing the water in it to determine the progress of the decontamination with a view of adding additional water and/or chemical to the open outer shells.

Other features and advantages will hereinafter appear.

In the accompanying drawings:

FIG. 1 is a schematic view showing the beginning portion of a succession of work-treating and rinsing tanks showing the tanks in cross section.

FIG. 1A is a continuation of the tanks shown in FIG. 1 for continuing the treatment and rinsing of work.

FIG. 2 is a cross section of a tank taken 90 from the sections shown in FIG. 1.

FIG. 3 is a view of a liquid treating tank which may continue the treatment of the rinsing water.

FIG. 4 shows another form of water treating tanks.

As shown in FIGS. 1 and 1A of the accompanying drawings, there is a series of spaced tanks 10, above which there is shown means for conveying the work from the last plating tank to the tanks of the present invention, comprising a rail 11 having trucks 12 spaced from each other by rods 11a. From each truck depends a cable 13 carrying a work carrier 14, such as a basket, barrel or rack. By operation of suitable means not shown, the work carriers 14 are lowered into and raised from the tanks and conveyed from one tank to the next.

According to the present invention, each tank 10 has an outer shell 15 and a substantially smaller inner shell 16. The inner shell 16 is supported in the outer shell with its walls 17 spaced relative to the walls 18 of the outer shell 15. The inner shell 16 is large enough to receive the work and work carriers 14 which are immersed in and withdrawn from the inner shell 16 periodically by the cable 13, all the work carriers 14 being lowered into and raised from the inner shells l6 and being advanced from tank to tank so that each work carrier progresses from one tank to the next in the operation of rinsing and treating the work.

To supply fresh water to the inner shells 16 of the tanks 10, there is a water supply pipe 19 having an outlet 20 controlled by a valve 21 over each inner shell 16.

As stated above, the inner shells 16 of the tanks 10 may contain, in addition to water, material for treating the work as it progresses from tank to tank, for instance by oxidation, reduction, neutralization, or pH change to partially remove the cyanides, zinc metal and impurities from the surface of the work.

In those tanks 10, in the inner tank 16 of which work is to be chemically treated, the space between the outer shell 15 and the inner shell 16 is closed so that the chemical materials in the inner shell 16 cannot overflow into its outer shell 15. For this purpose, the top of the inner shell 16 of certain tanks may be provided with a horizontal flange 24 and a vertical flange 25 which may be welded or otherwise secured to to the top portion of the outer shell 15.

As shown in FIG. 1, the tank I is an open top tank and the inner shell 16 may contain water to rinse off the plating solution carried by the work. After a predetermined lapse of time required for the plating process, the work carrier 14 is transferred to the inner shell of the tank II where the work is rinsed in water from the water supply line 19.

When the work is inserted in the inner shell of tank II some of the liquid in the inner shell 16 which is already contaminated by a preceding batch of work overflows into the outer shell 15. Liquid equal to the displacement of the work and work carrier 14 flows through the piping 27 from the outlet 28 at the bottom of the outer shell of the tank I] to the inlet 29 of the tank III, the liquid carrying with it chemical material which was placed in the outer shell of rinsing tank I. The outer shell 15 of tank Ill has a closed top and acts as a holding tank while the inner shell 16 is supplied with acidic or neutralizing material.

In the next operation of the conveyor system, the advanced work carrier 14 is transferred to the inner shell 16 of tank IV where the work is rinsed, the overflow being passed to the outer shell 15 of tank IV and through the piping 27 to the inlet 29 of the outer shell of tank V which has a closed top. The inner shell of tank V in the example given is provided with chromates to chemically polish or passivate the work.

It should be noted that the inlets 29 of the tanks I, II, III, IV and V are all at the same level. This is because the bottom of the outlet 30 of tank V is just above the top of the inlets 29 of tanks I, II, III, IV and V. Hence, with the immersion of the work in tanks I, II and IV, the flow of the liquid out of the tank V will approximately equal the displacement of the work in tanks I, II and IV. The treating of the cyanide bearing rinse water may be terminated after leaving tank V if the water is sufficiently decontaminated, and the rinse water may then be passed through a valve 31., filter 32 and pipe 33 and be discharged or reused if sufficiently decontaminated.

If the work is treated by the chemicals in tank V, it may be transferred to tank VI (FIG. 1A) in which it is rinsed, the liquid displaced therefrom flowing to the tank VII through the piping 27 where it is held in the outer shell 15 of the tank VII. The inner shell 16 of tank VII may contain dichromates for further treatment of the work. The outer shell 15 being closed at the top serves merely as a holding tank to give the reagents time to act on the rinse water received from tank Vl.

From the tank VII the rinse water flows to the tank VIII through piping 27 when the work is immersed in tank VI. In tank VIII, the rinse water is treated if necessary by adding reagents thereto to get rid of excess chrome carried over by the work from tanks V and VII.

Displaced liquid from tank VIII flows into the outer shell of tank IX (which is a rinsing tank) through piping 27 where the water is subjected to further treatment before it is allowed to flow through outlet pipes 30 and filter 32 to be reused or to be passed to the sewer pipe 33.

One of the advantages of the batch method of treating contaminated liquid to rinsing plated work is that the progress of the purification can be determined as the liquid progresses from tank to tank. This may be done by placing in certain of the tanks, for instance tanks II, IV, VI, VIII and IX, instruments 34 for determining the acidity and alkalinity of the fluid and adding additional or other reagents through the open tops of the outer shells of the tanks as needed.

If it is found that the liquid in tank V or IX is not sufficiently free from contamination to be disposed of or reused, additional holding means may be added to the series.

As shown in FIG. 3, a structurally single holding tank X may be provided to progressively treat the liquid issuing from the work treating tank V or IX. For this purpose, the tank X comprises separator plates 35 and 36, and forming compartments 37 and 38, the plates 35 being open at the bottom to permit the liquid to flow from the compartment 37 to the compartment 38, and the plates being shorter than the sides 39 of the tank so that water under treatment may overflow the plates 36 and into the compartment 37 and so on through the succeeding compartments. The tank X may have an inlet pipe 40 connected to the outlet 30 of tank V, or to the outlet 30 of tank IX if tanks VI to IX are used, and an outlet pipe 41 leading to the filter 32' and pipe 33' reuse of the rinse water or to the sewer if the rinse water is not to be reused. Suitable chemicals to treat the liquid may be added thereto through the open top of tank X.

The piping 27 connecting adjacent tanks may each be provided with a valve 42 and piping connecting to the sewer. Check-valves 43 may be placed in the line 27.

As shown in FIG. 4, the tanks XI, XII and XIII may be situated beyond the tank V or the tank IX from which the work is removed from the conveyor. The tanks XI, XII and XIII may constitute holding tanks and may receive chemicals to further treat the rinse water as it flows from tank to tank.

It is within the scope of the present invention to utilize tanks such as tanks XI, XII and XIII as batchholding tanks in purifying any contaminated liquid.

It is also within the scope of this invention to connect separately tank I, VI or VIII to the unitary three compartment tank such as shown in FIG. 3.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

I claim:

1. Apparatus for treating water in which work coming from a plating tank has been rinsed, comprising a series of holding tanks; means for conducting rinse water to a first holding tank; means for conducting batches of rinse water from tank to tank, certain of said tanks having outer shells and work-treating inner shells, the latter being adapted to be filled to overflowing with water and so positioned in the outer shells that water in said inner shells may overflow into said outer shells; means for immersing successive batches of work into the water in said inner shells to rinse the work, the immersion of the work causing the water in the inner shells to overflow into the outer shells; means for maintaining a uniform level of water in the outer shells of the tanks as it flows from tank to tank, the water in at least several of the outer shells being accessible for chemical testing and being open to receive chemicals to treat the water; and means for discharging rinse water from the outer shell of the terminal tank of a series of tanks for the disposal or reuse of the treated rinse water.

2. Apparatus for treating water as defined in claim I in which said holding tanks are separate structures connected by piping leading from the bottom of one tank to the upper portion of an adjacent tank.

3. Apparatus as defined in claim 1 in which certain of said inner shells are work-treating shells adapted to receive work-treating water and chemicals, said worktreating shells having means for preventing the overflow of said water and chemicals to their respective outer shells.

4. Apparatus as defined in claim 1 in which there are means in certain of said outer shells for chemically testing the rinse water therein.

5. Apparatus as defined in claim 1 in which said means for maintaining a uniform level of water in the outer shells as it flows from tank to tank comprises water-conducting pipes and including a back-check valve between adjacent tanks.

6. Apparatus as defined in claim VI in which there are means for supplying make up rinse water to said inner shells.

7. Apparatus for continuously treating and rinsing successive batches of plated work comprising a succession of tanks having inner shells, each having an open top of a size to receive a work carrier and work carried thereby, and outer shells which are substantially larger than the inner shells, certain of said inner shells being work-rinsing shells adapted to overflow or be filled to overflowing with rinse water and being positioned in said outer shell so that overflow of water is caught by the associated outer shell, others of said inner shells being work-treating shells adapted to receive normal processing chemicals and having means to prevent overflow of liquid into their associated outer shells; means for advancing batches of work from tank to tank from the last plating tank and immersing and removing said batches of work in succeeding inner shells; and means for conducting the overflow water from one outer shell to the next outer shell and disposing of the rinse water to a suitable outlet to be discarded or reused if and when sufficiently free from contamination.

8. The method of treating contaminated water in which work coming from a plating tank has been rinsed, which comprises the steps of holding the rinse water in a series of holding tanks having outer shells and rinsing shells within and spaced from said outer shells; filling certain of said rinsing shells with water to overflowing; immersing batches of plated work in the water in said rinsing shells which causes the rinsing water in each rinsing shell to overflow into its outer shell and causes the rinsing water in the outer shells to flow from tank to tank; testing the rinse water in various of said tanks as the water advances from tank to tank; applying decontaminating chemicals as required to the water in said tanks; and disposing of or reusing said rinse water when it is sufficiently decontaminated.

9. The method as defined in claim 8 in which certain of said rinsing shells are isolated from their outer shells by the space between both shells being closed off; and

placing neutralizing chemicals in the water of said isolated rinsing shells to treat work in batches between said rinsing operations.

10. The method as defined in claim 9 which includes waterthe steps of advancing said batches of work from the 

1. APPARATUS FOR TREATING WATER IN WHICH WORK COMING FROM A PLATING TANK HAS BEEN RINSED, COMPRISING A SERIES OF HOLDING TANKS; MEANS FOR CONDUCTING RINSE WATER TO A FIRST HOLDING TANK; MEANS FOR CONDUCTING BATCHES OF RINSE WATER FROM TANK TO TANK, CERTAIN OF SAID TANKS HAVING OUTER SHELLS AND WORKTREATING INNER SHELLS, THE LATTER BEING ADAPTED TO BE FILLED TO OVERFLOWING WITH WATER AND SO POSITIONED IN THE OUTER SHELLS THAT WATER IN SAID INNER SHELLS MAY OVERFLOW INTO SAID OUTER SHELLS; MEANS FOR IMMERSING SUCCESSIVE BATCHES OF WORK INTO THE WATER IN SAID INNER SHELLS TO RINSE THE WORK, THE IMMERSION
 2. Apparatus for treating water as defined in claim 1 in which said holding tanks are separate structures connected by piping leading from the bottom of one tank to the upper portion of an adjacent tank.
 3. Apparatus as defined in claim 1 in which certain of said inner shells are work-treating shells adapted to receive work-treating water and chemicals, said work-treating shells having means for preventing the overflow of said water and chemicals to their respective outer shells.
 4. Apparatus as defined in claim 1 in which there are means in certain of said outer shells for chemically testing the rinse water therein.
 5. Apparatus as defined in claim 1 in which said means for maintaining a uniform level of water in the outer shells as it flows from tank to tank comprises water-conducting pipes and including a back-check valve between adjacent tanks.
 6. Apparatus as defined in claim 1 in which there are means for supplying make up rinse water to said inner shells.
 7. Apparatus for continuously treating and rinsing successive batches of plated work comprising a succession of tanks having inner shells, each having an open top of a size to receive a work carrier and work carried thereby, and outer shells which Are substantially larger than the inner shells, certain of said inner shells being work-rinsing shells adapted to overflow or be filled to overflowing with rinse water and being positioned in said outer shell so that overflow of water is caught by the associated outer shell, others of said inner shells being work-treating shells adapted to receive normal processing chemicals and having means to prevent overflow of liquid into their associated outer shells; means for advancing batches of work from tank to tank from the last plating tank and immersing and removing said batches of work in succeeding inner shells; and means for conducting the overflow water from one outer shell to the next outer shell and disposing of the rinse water to a suitable outlet to be discarded or reused if and when sufficiently free from contamination.
 8. The method of treating contaminated water in which work coming from a plating tank has been rinsed, which comprises the steps of holding the rinse water in a series of holding tanks having outer shells and rinsing shells within and spaced from said outer shells; filling certain of said rinsing shells with water to overflowing; immersing batches of plated work in the water in said rinsing shells which causes the rinsing water in each rinsing shell to overflow into its outer shell and causes the rinsing water in the outer shells to flow from tank to tank; testing the rinse water in various of said tanks as the water advances from tank to tank; applying decontaminating chemicals as required to the water in said tanks; and disposing of or reusing said rinse water when it is sufficiently decontaminated.
 9. The method as defined in claim 8 in which certain of said rinsing shells are isolated from their outer shells by the space between both shells being closed off; and placing neutralizing chemicals in the water of said isolated rinsing shells to treat work in batches between said rinsing operations.
 10. The method as defined in claim 9 which includes the steps of advancing said batches of work from the last isolated rinsing shell and immersing the batches progressively in a series of rinsing shells containing only rinse water before finally disposing of or reusing said water. 